1. Field of the Invention
The present invention is directed to a system for increasing efficiency in the generation of mechanical and/or electrical energy in a gas turbine plant by making optimum use of the heat occurring in a gas turbine plant through incorporation of additional work-performing fluid circuits and through incorporation of solar energy in the gas turbine plant.
2. Description of the Related Art
The basic principle of a conventional gas turbine plant consists in that fresh air is compressed in an air compressor and is then burned in a combustion chamber by supplying a fuel to form a high-energy hot gas and is subsequently expanded in a work-performing manner in the turbine part of the gas turbine plant. A portion of the obtained energy is consumed to drive the air compressor and the remainder can be converted into useful electrical energy. Conversion into useful electrical energy is carried out by means of a generator for converting mechanical energy into electrical energy, which generator is connected to the turbine part of the gas turbine plant. In doing so, the turbine part is fed by the hot gas which is generated in the combustion chamber and which is under high pressure. In many practical applications, for example, in pipeline compressor stations, this hot gas which is still hot is subsequently released wastefully into the environment via the exhaust gas stack of the gas turbine plant.
Based on the growing demand for energy and the goal of appreciably reducing CO2 emissions, it is necessary to increase the efficiency of plants for generation of mechanical and/or electrical energy.
Combined cycle plants comprising gas turbines and steam turbines in which the advantageous characteristics of the gas turbine plant are joined with those of the steam turbine plant have been known for many years in the prior art for increasing total efficiency. Gas turbine plants and steam turbine plants in which solar energy is incorporated have also been known for some years. Depending on the layout of the plants, widely varying parameters of work media and the associated loading of the respective plant components must be taken into account, and the respective use of solar input of solar energy can accordingly lead to elaborate and therefore costly concepts.
Previous solar energy plants built on a large industrial scale are based on what is known as parabolic trough technology in which the solar energy is coupled into the conventional steam power process by thermal oil circuits; but only relatively low process efficiencies can be achieved due to the relatively low upper process temperature.
By bundling solar energy by means of heliostats in a solar tower, the upper process temperature can be increased appreciably approximately 950° C. so that the process efficiencies achieved in combined gas/steam turbines are higher than in parabolic mirror technologies. However, the investment costs are very high; moreover, sites in areas with severe water shortages and high solar radiation suggest the necessity of developing other systems.
In the combined cycle plants mentioned above, higher efficiencies can only be achieved by means of high exhaust gas temperatures in the gas turbine plants and, for reasons relating to thermodynamics, this requires a high input temperature in the turbine part of the gas turbine plant and a corresponding optimum pressure ratio of the compressed combustion air generated in the compressor part of the gas turbine plant. The high thermal loads on the blading in the turbine part of the gas turbine plant which then inevitably result from this require correspondingly high amounts of cooling air which are generally withdrawn downstream of the air compressor and, therefore, lead to a significant reduction in overall efficiency.
While the input temperatures in the gas turbine plant have a decisive influence on the level of electric power of the gas turbine plant, the pressure or pressure ratio of the gas turbine plant at the output of the compressor part of the gas turbine plant determines the efficiency.
Accordingly, it is an object of the present invention to provide a system for a noticeably more efficient total plant for achieving a higher work output for generating mechanical and/or electrical energy while at the same time mitigating the above-mentioned disadvantages.